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At least 289 records · Page 16Linked to original sources
PubMed1986

Radioimmunoassay for detection of the Snow Mountain Agent of viral gastroenteritis.

The Snow Mountain Agent (SMA) is a Norwalk-like viral agent of acute gastroenteritis that has been detected only by immune electron microscopy (IEM). We established a solid phase microtiter radioimmunoassay (RIA) for SMA antigen employing pre-and post-challenge sera from volunteer studies as capture antibodies. SMA was detected in 12 of 67 stool samples from volunteers who were ill after oral challenge with SMA. All samples in which virus particles were detected by IEM were positive by RIA, but the RIA was 10-80 times more sensitive than IEM. To detect serum antibody to SMA, a blocking test was developed, employing diarrheal stool containing SMA as a standard source of antigen. Serum antibody rises were detected in eight out of nine volunteers with experimentally induced illness following challenge with SMA, as well as in three out of three naturally occurring cases. A preliminary sero-epidemiologic survey suggested that infection with SMA was common in the population surveyed. This RIA should permit large scale seroepidemiologic studies of SMA to be carried out, and should also facilitate characterization of this agent.

Adolescent↗
PubMed2005

Hyperbranching induced by cold-shock or snow-flake mutation in Neurospora crassa is prevented by addition of exogenous calcium.

Hyphal tip growth is a highly polarized process of cell extension, which may be affected by chemical and physical stress. Neurospora crassa exposed to cold-shock lost its polarized growth and dichotomous branches were detected. These effects were not observed in the presence of 500 mM Ca2+. We compared here the morphological pattern of a snow-flake mutant (sn) and the wild-type (wt) exposed to 4 degrees C. Hyphal morphology, nuclei, actin and microtubule distribution were analyzed. No effects on sn hyphal morphology were detected at 4 degrees C. Exogenous Ca2+ converted sn to an essentially wt appearance. The results presented here suggest that sn mutation and cold-shock treatment have affected Ca2+ influx since addition of this cation to sn (30 degrees C) and to wt (4 degrees C) maintained polarized growth and normal nuclear and microtubules distribution.

Actins↗
PubMed2000

Reanalysis and New Measurements of N(2) and CH(4) Adsorption on Ice and Snow.

Numerous literature data indicate that the mean heat of adsorption of a monolayer of N(2) (DeltaQ(N(2))) on ice or snow at 77.15 K, determined by volumetric methods, is highly variable, suggesting that ice surface properties strongly depend on its mode of formation and its thermal history. Less numerous data on CH(4) adsorption show smaller variations of DeltaQ(CH(4)). If such variations are real, the extrapolation to atmospheric chemistry models of adsorption parameters measured on laboratory-made ice may be unwarranted. We have measured CH(4) adsorption on variable amounts of a crushed ice sample, to show that when the total surface area of the sample is below a threshold value, DeltaQ(CH(4)) decreases. We identify the cause of this artifact as an error in the molar budget, because the temperature gradient in the tube connecting the introduction and expansion volumes is not taken into account. Performing an adequate molar budget suppresses this artifact, except for ice samples with very small total surface areas, where the resolution of the manometer becomes a limiting factor and a further decrease in DeltaQ(CH(4)) is observed. Error in DeltaQ(gas) results in large errors in surface area, and we suggest that the value of DeltaQ(gas) obtained can be used to test the reliability of the surface area measurement. Copyright 2000 Academic Press.

Journal Article↗
PubMed1999

A new avian hepadnavirus infecting snow geese (Anser caerulescens) produces a significant fraction of virions containing single-stranded DNA.

We describe the identification and functional analysis of an evolutionary distinct new avian hepadnavirus. Infection of snow geese (Anser caerulescens) with a duck hepatitis B virus (DHBV)-related virus, designated SGHBV, was demonstrated by detection of envelope proteins in sera with anti-DHBV preS and S antibodies. Comparative sequence analysis of the PCR-amplified SGHBV genomes revealed unique SGHBV sequence features compared with other avian hepadnaviruses. Unlike DHBV, SGHBV shows an open reading frame in an analogous position to orthohepadnavirus X genes. Four of five cloned genomes were competent in replication, gene expression, and virus particle secretion in chicken hepatoma cells. Primary duck hepatocytes were permissive for infection with SGHBV, suggesting a similar or identical host range. SGHBV was found to secrete a significant fraction of virion-like particles containing single-stranded viral DNA. This was observed both in cell culture medium of SGHBV DNA-transfected LMH cells and in viremic sera of several birds, suggesting that it is a stable trait of SGHBV. Taken together, SGHBV has several unique features that expand the knowledge of the functional and evolutionary diversity of hepadnaviruses and offers new experimental opportunities for studies on the life cycle of hepadnaviruses.

Amino Acid Sequence↗
PubMed1976

Assortative mating in lesser snow geese (Anser caerulescens).

Assortative mating occurs in the dimorphic lesser snow geese in the wild. Mixed matings between the blue and white phases are much less frequent than would be expected by chance. Evidence from marked birds in field conditions indicated that mate choice was correlated with familial color. Birds from white families usually chose white mates, birds from blue families usually chose blue mates, and birds from mixed families chose mates of either color. Similar results were obtained under captive conditions when offspring from foster families with particular parental and offspring color combinations were allowed to choose mates. Both parental color and sibling color appeared to influence mate choice. The bird's own color did not appear to be important in mate choice in either field or experimental conditions, and in those cases where male and female parents differed in color neither parental color was more influential than the other in determining offspring mate choice. The results provide the first evidence, to our knowledge, that mate selection based on familial appearance operates intraspecifically in the wild.

Animals↗
PubMed1998

Trace Element Concentrations in Two Subpopulations of Lesser Snow Geese from Wrangel Island, Russia

Lesser snow geese (Anser c. caerulescens) from the Wrangel Island, Russia breeding colony spend the winter in two widely separated areas: the northern subpopulation in southern British Columbia and northern Washington and the southern subpopulation in the Central Valley of California. We examined 19 trace elements in the eggs and livers of geese from these two subpopulations to examine whether geese from the different wintering areas have similar trace element burdens. Eggs collected at the breeding colony from geese of the southern subpopulation had slightly higher levels of manganese, an element that can cause neurological damage and behavioral changes in chicks, than geese of the northern subpopulation. Livers from adult geese collected on the two wintering areas showed significant differences in trace elements including copper, iron, magnesium, molybdenum, and zinc. Copper concentrations in the livers of geese from the southern subpopulation were much higher than those from the northern subpopulation (&xmacr; = 116 vs. 46 ppm; dry weight). Elevated levels of copper may induce anemia in birds. The differences in trace element concentrations of these two subpopulations may be related to farming practices in their wintering areas. Geese from the northern subpopulation feed in pastures and coastal marshes and migrate along the coast, but geese from the southern subpopulation feed predominantly in rice fields and migrate over farm land. Copper and manganese are major components of fertilizers and fungicides commonly applied during rice cultivation.

Journal Article↗
PubMed1997

Human calicivirus genogroup II capsid sequence diversity revealed by analyses of the prototype Snow Mountain agent.

The Snow Mountain agent (SMA) is the prototype genogroup II and serotype 3 human calicivirus responsible for epidemic outbreaks of acute gastroenteritis. We have cloned the region of the SMA genome that encodes the single capsid protein. The predicted amino acid sequence of the capsid protein is distinct from other calicivirus strains that have been termed SMA-like based on sequence similarity between the RNA polymerase regions and IEM reactivity. In a previous report, a high sequence similarity in a small region of the RNA polymerase between SMA and another strain, OTH-25, suggested that the capsid proteins of OTH-25 and SMA would be very similar. In this report, we show that the capsid proteins of OTH-25 and SMA are more distinct than was predicted by similarity in the RNA polymerase. In addition, phylogenetic analysis of a region of the RNA polymerase and of the N-terminal conserved domain of the capsid protein of 12 human caliciviruses resulted in trees with different topologies, suggesting that recombination has occurred within this group of viruses. Molecular characterization of the prototype calicivirus strains is important in determining the relationships between capsid similarity at the amino acid level, genetic grouping by sequence comparison, and antigenic reactivity.

Amino Acid Sequence↗
PubMed2005

Modulations of the thylakoid system in snow xanthophycean alga cultured in the dark for two months: comparison between microspectrofluorimetric responses and morphological aspects.

The response of the plastid was studied, with a special emphasis on thylakoid structure and function, in a snow filamentous xanthophycean alga (Xanthonema sp.) incubated in darkness for two months. Microspectrofluorimetric analyses were performed on single living cells to study the variations in the assembly of the chlorophyll-protein complexes of photosystem II, in comparison with cells grown in light. In parallel, changes in micro- and submicroscopic plastid morphology and in photosynthetic pigment content were monitored. Throughout the experiment, the lamellar architecture of thylakoids in the alga was relatively well preserved, whereas photosystem II underwent disassembly and degradation triggered by prolonged darkness. Conversely, the light-harvesting complex of photosystem II proved to be relatively stable for long periods in darkness. Moreover, a role of the peripheral antennae in determining thylakoid arrangement in xanthophycean algae is implied. Although the responses observed in Xanthonema sp. can be considered in terms of acclimation to darkness, the progressive destabilisation of the light-harvesting complex of photosystem II testifies to incipient ageing of the cells after 35 days.

Eukaryota↗
PubMed1984

Surface EMG and torsion measurements during snow skiing: laboratory and field tests.

The relationship between mean rectified EMG (MREMG) measured with surface electrodes and the longitudinal torsion of the lower extremity was investigated in laboratory and snow skiing experiments. Linear regression of the MREMG from the gluteus medius and the peroneus longus with the torsion measured at the foot in the laboratory tests showed that torsion can be predicted with correlation coefficients greater than 0.95 and with a standard deviation less than 5 Nm over all knee flexions and weight bearing. A similar correspondence between MREMG and torsion during skiing does not exist. MREMG is dominantly correlated to posture and body position control functions in skiing. During falling, during ski binding release, and during possible injury sustaining situations, the MREMG was always relatively large, but it was not distinguishable from that associated with smaller torsion of the lower extremity.

Adult↗
PubMed1985

A microcomputer controlled snow ski binding system--I. Instrumentation and field evaluation.

This paper presents the design and field evaluation of the first microcomputer controlled ski binding system. This system incorporates an Intel 8086 microcomputer controller and an integral binding/dynamometer. This instrumentation system not only undertakes real time control, but also it records dynamometer data via a miniature digital cassette tape recorder. The integral binding/dynamometer offers the same operational and mounting convenience of commercially available mechanical bindings. The binding may be released either manually or electrically via the controller. Comprised of four octagonal half strain rings, the strain gage dynamometer measures the three moment load components at the boot. To enable the user to conveniently operate the computer, extensive operating software was developed. The operating software is discussed in relation to both the acquisition and storage of data from the dynamometer and the control of the electro-mechanical snow ski binding. The binding system has been used successfully to both record boot moment components and control ski binding release during actual skiing maneuvers. Moment histories typical of three common recreational skiing maneuvers are presented.

Athletic Injuries↗
PubMed1989

Seminoma and parathyroid adenoma in a snow leopard (Panthera unica).

A seminoma and parathyroid adenoma were diagnosed in an aged snow leopard. The ultrastructural appearance of the seminoma was similar to that described in the dog and in man. The lack of significant amounts of rough endoplasmic reticulum, Golgi complexes and free ribosomes in the parathyroid adenoma suggested that it was non-functional. Parathyroid adenoma has not been previously described in a large wild feline.

Adenoma↗
PubMed1981

A clinical, genetic, and ultrastructural study of snow-capped teeth: amelogenesis imperfecta, hypomaturation type.

Snow-capped teeth (SCT) is a rare form of amelogenesis imperfecta, hypomaturation type. It has been alluded to on numerous occasions but, to our knowledge, no pedigree or clinical-histopathologic data have been published. In this report, two families are described. Scanning electron microscopic (SEM) studies of unetched teeth from affected persons revealed numerous defects of the enamel surface. After etching with 10 percent hydrochloric acid for 21/2 minutes to remove the outer prismless layer of enamel, SEM features of the enamel prism were essentially identical to those of normal teeth. These findings suggest that the structural defect in SCT is confined to the outer prismless enamel layer and that the bulk of the enamel is normal. The genetic analysis supports the concept that SCT is inherited in an X-linked recessive fashion and not as an autosomal dominant trait, as previously reported.

Adolescent↗
PubMed1984

Occupational asthma in snow crab-processing workers.

The prevalence of occupational asthma was studied in two snow crab-processing industries in operation since 1980. Before the 1982 season, all except 10 of the 313 employees were investigated by a questionnaire, prick skin tests with common allergens, crab n and crab-boiling water extracts, and spirometry. The diagnosis was confirmed in 46 (15.6%) workers (including 33 of 64 subjects with a history highly suggestive of occupational asthma in the previous seasons) by (1) specific inhalation challenges in 33 subjects (one immediate, nine dual, and 23 late asthmatic responses) and/or (2) a combination of monitoring of peak expiratory flow rates (n = 12) and significant changes in bronchial responsiveness to histamine (n = 16) as well as in spirometry (n = 18) after reappearance of symptoms on return to work. Positive skin tests to crab (p less than 0.001) and, to a lesser degree, smoking history (p = 0.03) but not atopy (p greater than 0.05) were related to the presence of occupational asthma. A high prevalence of rhinoconjunctivitis (35 of 46) and urticaria (16 of 46) was also documented in the affected individuals.

Asthma↗
PubMed1983

A new photographic method for mapping spatio-temporal receptive field using television snow stimulation.

A means was devised to measure simultaneously spatial as well as temporal characteristics of visual receptive fields by stimulating the retina with the noise obtained on an unused television channel. The input, television snow, and the output, neural response, were recorded on a video tape. The tape was played back to obtain the (linear) spatio-temporal Wiener kernel by cross-correlating the input with the output. This method can be applied to extract the linear part of the visual responses in time and space.

Animals↗
PubMed2006

Phaeohyphomycosis in a snow leopard (Uncia uncia) due to Cladophialophora bantiana.

Phaeohyphomycosis caused by Cladophialophora bantiana was diagnosed in a 5-month-old snow leopard with spastic paralysis of the hind legs and inability to defaecate or urinate. At post-mortem examination, a greenish soft mass resembling an abscess was found on one side of the epidural space at the fourth lumbar vertebral body. Histological examination revealed a purulent meningitis with myelomalacia. Dematiaceous fungal hyphae, present within the inflammatory infiltrate, were identified as C. bantiana by culture and sequence analysis of the 18S ribosomal RNA gene. This neurotropic fungus rarely affects organs other than the brain in human beings and cats, and has been reported only occasionally in Europe. The case described suggests that phaeohyphomycosis due to C. bantiana infection may be recognized more frequently in the future and the possible involvement of organs other than the brain should be borne in mind.

Animals↗
PubMed2004

John Snow, William Farr and the 1849 outbreak of cholera that affected London: a reworking of the data highlights the importance of the water supply.

OBJECTIVES: This paper examines why Snow's contention that cholera was principally spread by water was not accepted in the 1850s by the medical elite. The consequence of rejection was that hundreds in the UK continued to die. METHODS: Logistic regression was used to re-analyse data, first published in 1852 by William Farr, consisting of the 1849 mortality rate from cholera and eight potential explanatory variables for the 38 registration districts of London. RESULTS: Logistic regression does not support Farr's original conclusion that a district's elevation above high water was the most important explanatory variable. Elevation above high water, water supply and poor rate each have an independent significant effect on district cholera mortality rate, but in terms of size of effect, it can be argued that water supply most strongly 'invited' further consideration. CONCLUSIONS: The science of epidemiology, that Farr helped to found, has continued to advance. Had logistic regression been available to Farr, its application to his 1852 data set would have changed his conclusion.

Altitude↗
PubMedDate not supplied

Hydrogen peroxide enteritis: the "snow white" sign.

Hydrogen peroxide is a useful disinfectant that has achieved widespread utility in varied clinical settings. We report an epidemic of hydrogen peroxide enteritis that developed in seven patients in our gastrointestinal endoscopy unit during a 2-week period in early 1988. During endoscopy, using recently sterilized endoscopes that were flushed with 3% hydrogen peroxide after the glutaraldehyde cycle, instantaneous blanching (the "snow white" sign) and effervescence were noted on the mucosal surfaces when the water button was depressed. No patient subsequently suffered morbidity or mortality associated with this peroxide enteritis, and the biopsy specimens revealed nonspecific inflammation. The toxicity of hydrogen peroxide when used in enema form is reviewed, as well as the pathogenesis of peroxide enteritis.

Aged↗